This invention relates to the use of a modified natural clinoptilolite as a catalyst in a process for the conversion of propane and butane.
Synthetic zeolite catalysts have been used for many years in the chemical and petrochemical industry; for example, Zeolite Y is used in hydrocarbon cracking processes. More recently it has been found that the synthetic Zeolite ZSM-5, suitably modified, e.g., by the addition of zinc or gallium compounds, can convert propane and butane into hydrocarbons rich in benzene, toluene and xylenes. This process, known as the CYCLAR process (which is referred to in a paper presented at the N.P.R.A. Annual Meeting, San Antonio, Tex., March 1987, J. A. Johnston, J. A. Weiszmann, G. K. Hiler and A. H. Hall) is useful in the preparation of high octane gasoline from propane and butane. This conversion process does not yield high selectivities to ethene and propene. The chemical industry would prefer a process, and thus a catalyst for the process, which results in the formation of ethene and propene as well as C.sub.4 hydrocarbons, as these products are more flexible for further use. Further, the ZSM-5 zeolite catalyst is expensive and produces a very broad product range of aromatic compounds which are of poor suitability for use as chemical feedstocks.